Citing a document that summarized the meeting, the Times reported in May that Trump said the dismissal relieved "great pressure" on him. The Washington Post reported that Trump also shared classified, sensitive information related to the fight against the Islamic State during the meeting.

Mueller has also requested documents related to the firing of former National Security Adviser Michael Flynn, according to the Times. Flynn was forced from his position in February after it was revealed that he lied to Vice President Mike Pence about his contact with Russian ambassador Sergey Kislyak.

Two unidentified sources briefed on the requests told The Washington Post that the information requested spans 13 different categories "which investigators for the special counsel have identified as critical to their probe."

"The list demonstrates Mueller’s focus on key moments and actions by the president and close advisers which can address whether Trump sought to block the FBI investigations of Flynn and of Russian interference," the Post reported. "His team is also eyeing whether the president sought to obstruct the earlier Russia probe."